TY  - CHAP
A1  - Daniunas, A.
A1  - Komka, A.
A1  - Werner, F.
T1  - ANALYSIS AND DETERMINATION OF STRENGTH IN PLASTIC STAGE OF FREE FORM STEEL SHAPES
N2  - The steel structure design codes require to check up the member strength when evaluating plastic deformations. The model of perfectly plastic material is accepted. The strength criteria for simple cross-sections (I section, etc.) of steel members are given in design codes. The analytical strength criteria for steel cross-sections and numerical approaches based on stepwise procedure are investigated in many articles. Another way for checking the carrying capacity of cross-sections is the use of methods that are applied for defining strain-deformed state of elastic perfectly plastic systems. In this paper non-iterative methods are suggested for checking strength of cross-sections. Carrying capacity of cross section is verified according to extremum principle of plastic fail under monotonically loading and the strain-deformed state of cross-section is defined according to extremum energy principals of elastic potential of residual stresses and complementary work of residual displacements. The mathematical expressions of these principals for discrete cross-section are formulated as problems of convex mathematical programming. The cross-section of steel member using finite element method is divided into free form plane elements. The constant distribution of stresses along the finite element is accepted. The relationships of finite elements for static formulation of the problem are formed so, that kinematics formulation relationships could be obtained in a formal way using the theory of duality. Numerical examples of determination of cross-section strength, composition of interactive curves and composition of moment-curvature curves for different axial force levels are presented.
KW  - Stahlkonstruktion
KW  - Plastische Deformation
KW  - Mathematisches Modell
KW  - Finite-Elemente-Methode
Y1  - 2000
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-5803
ER  - 
TY  - JOUR
A1  - Staubach, Patrick
A1  - Machacek, Jan
A1  - Skowronek, Josefine
A1  - Wichtmann, Torsten
T1  - Vibratory pile driving in water-saturated sand: Back-analysis of model tests using a hydro-mechanically coupled CEL method
JF  - Soils and Foundations
N2  - The development of a hydro-mechanically coupled Coupled-Eulerian–Lagrangian (CEL) method and its application to the back-analysisof vibratory pile driving model tests in water-saturated sand is presented. The predicted pile penetration using this approachis in good agreement with the results of the model tests as well as with fully Lagrangian simulations. In terms of pore water pressure, however, the results of the CEL simulation show a slightly worse accordance with the model tests compared to the Lagrangian simulation. Some shortcomings of the hydro-mechanically coupled CEL method in case of frictional contact problems and pore fluids with high bulk modulus are discussed. Lastly, the CEL method is applied to the simulation of vibratory driving of open-profile piles under partially drained conditions to study installation-induced changes in the soil state. It is concluded that the proposed method is capable of realistically reproducing the most important mechanisms in the soil during the driving process despite its addressed shortcomings.
KW  - Plastische Deformation
KW  - Vibratory pile driving
KW  - Coupled-Eulerian–Lagrangian
KW  - Hydro-mechanically coupled
KW  - Hypoplasticity
KW  - Relative acceleration
KW  - Large deformation
KW  - Deformationsverhalten
KW  - Plastizität
KW  - OA-Publikationsfonds2020
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20210203-43571
UR  - https://www.sciencedirect.com/science/article/pii/S0038080620337586?via%3Dihub
VL  - 2021
IS  - Volume 61, Issue 1
SP  - 144
EP  - 159
PB  - Elsevier, Science Direct
CY  - Amsterdam
ER  -